The potential hidden age of dissolved organic carbon exported by peatland streams

Dean, J. F., Garnett, M. H. , Spyrakos, E. and Billett, M. F. (2019) The potential hidden age of dissolved organic carbon exported by peatland streams. Journal of Geophysical Research: Biogeosciences, 124(2), pp. 328-341. (doi: 10.1029/2018JG004650)

Abstract

Radiocarbon (14C) is a key tracer for detecting the mobilization of previously stored terrestrial organic carbon (C) into aquatic systems. Old C (>1,000 years BP) may be “masked” by postbomb C (fixed from the atmosphere post‐1950 CE), potentially rendering bulk aquatic dissolved organic C (DOC) 14C measurements insensitive to old C. We collected DOC with a modern 14C signature from a temperate Scottish peatland stream and decomposed it to produce CO2 under simulated natural conditions over 140 days. We measured the 14C of both DOC and CO2 at seven time points and found that while DOC remained close to modern in age, the resultant CO2 progressively increased in age up to 2,356 ± 767 years BP. The results of this experiment demonstrate that the bulk DO14C pool can hide the presence of old C within peatland stream DOC export, demonstrating that bulk DO14C measurements can be an insensitive indicator of peatland disturbance. Our experiment also demonstrates that this old C component is biologically and photochemically available for conversion to the greenhouse gas CO2, and as such, bulk DO14C measurements do not reflect the 14C signature of the labile organic C pool exported by inland water systems more broadly. Moreover, our experiment suggests that old C may be an important component of CO2 emissions to the atmosphere from peatland aquatic systems, with implications for tracing and modeling interactions between the hydrological and terrestrial C cycles.

• Item Type: Articles
• Additional Information: This work was supported 529 by the NERC Radiocarbon Facility NRCF010001 (allocation number 1855.1014). JFD 530 received partial support from the program of the Netherlands Earth System Science Centre 531 (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW) 532 (grant number 024.002.001).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Garnett, Dr Mark
• Authors: Dean, J. F., Garnett, M. H., Spyrakos, E., and Billett, M. F.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Journal of Geophysical Research: Biogeosciences
• Publisher: American Geophysical Union
• ISSN: 2169-8953
• ISSN (Online): 2169-8961
• Published Online: 22 February 2019
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Journal of Geophysical Research: Biogeosciences 124(2):328-341
• Publisher Policy: Reproduced under a Creative Commons license